At the present time there are a number of medical procedures which call for a prolonged period of injecting a liquid into a patient's veins, i.e., intravenous injection ("IV"). For example, an antibiotic drug in liquid form, or other "piggyback" fluids, may be injected for a period of 2 to 30 minutes, most often 10-15 minutes.
A number of devices have been suggested and are commercially available for such so-called "drip IV". The most commonly used device is a hand-operated (hand delivered) IV push syringe device. It requires a nurse, or other health-care professional, to push on a plunger for 2-20 minutes. That device requires the attention of an operator. It is labor-intensive and suitable personnel may not always be available when they are needed for such hand-delivered IV medication. In addition, the operator is not always able to push on the device with a constant pressure, for example, due to inattention or fatigue. Since the operator's hand pressure is not constant, the delivery of the drug is also uneven, which is generally undesirable. Another device is a motor driven precision infusion pump. However, such pumps are expensive, may require specially trained personnel, and may not be suitable for home use.
U.S. Pat. No. 5,476,449 shows a syringe for injecting fluids using an intravenous (IV) infusion tube having a connector. A syringe plunger is slidably disposed in the syringe.
In U.S. Pat. No. 4,245,655 entitled "Blood Collection Device" a syringe has the distal end of a plunger received in its chamber and a collection bag made of flexible material. When the plunger is withdrawn it causes a vacuum around the bag so that the bag fills with blood and expands.
U.S. Pat. No. 5,032,117 discloses a syringe for the gravity-feeding of IV drugs. The syringe is suspended above the patient. A needle penetrates a stopper to vent the interior to ambient air.